This module provides incremental statistical folds based upon the foldl library

An incremental statsitical fold can be thought of as exponentially-weighting statistics designed to be efficient computations over a Foldable.

Some throat clearing is required, however.

The common usage term "exponential moving ..." refers to the cumulative effect
of the fold referencing the original data. From the point of view of a
single step, the algorithm could be better described as "constant proportion" or
"geometric" decay. Many other methods are also possible and future versions of the library may introduce some more.

A main point of the library is that the traditional simple moving average
uses a sliding window of past data and thus requires keeping track of
the last n elements in State (in a LIFO queue most likey). It may be simple for the human brain but its a more complex and costly computational than this single-pass version.

For clarity, moving average (and moving whatever) below refers to geometric decay
rather than the common usage. So with the throat clearing out of the way: